Process for the recovery of oil from tar sands using granulated coke



Oct. 20, 1964 J. A. BICHARD 3,

PROCESS FOR THE RECOVERY OF OIL FROM TAR SANDS usmc GRANULATED coma Filed May a, 1961 3 FIGURE F== 7 I I I 6 2 a s i .Li 9 lo TAR SANDS MIX MECHANICAL SEPARATION FIGURE 2 2 9 70-795; 5 mm. mxms: |oo% on. RECOVERY m E 80 Q 25% COKE 05 g 911 25 5 O 5 I I: 60 I g 25 40 T I SHEAR ONLY, 8 NO COKE I 3 20 i Q I Z I (0 254 1 5 0 50 I00 I50 200 TOTAL WATER m mxme, wT. ON TAR smos John A. Bichord INVENTOR PATENT ATTORNEY United States Patent 3,153,625 PROCESS FOR THE RECOVERY OF GIL FROM TAR SANDS USING GRANULATED (IOKE John A. Richard, Point Edward, Ontario, Canada, as-

signor to Esso Research and Engineering Company, a

corporation of Delaware Filed May 8, 1961, Ser. No. 108,532

9 Claims. (Cl. 208-11) The present invention is generally concerned with the recovery of hydrocarbons from tar sands. The invention is more particularly concerned with an improved technique of efi'iciently removing hydrocarbons, such as bitumen, tars, and the like from tar sands containing the same, such as Athabaska tar sands. The invention is particularly concerned with the use of carrier particles in an improved integrated process for the recovery of oil from tar sands. In one operation or an initial phase the process comprises removing substantially oil-free sand from a quantity of tar stands as mined, thereby increasing the concentration of the tar or bitumen on the remaining sands. This bitumen-rich sand is then further handled in a secondary phase, such as a thermal phase or a solvent treating phase, in order to substantially completely recover the bitumen from the bitumen-rich sands. A specific adaptation of the invention comprises an integrated process wherein in an initial operation, the concentration of the bitumen is increased on a certain quantity of sand and then this bitumen-rich sand is handled in a coking operation such as a fluid type coking operation. The carrier particles or granulated carriers may be non-porous as for example stones, but are-preferably a hydrocarbon adsorbent as for example coke particles such as are secured in a fluid coking operation. In essence, the operation comprises mixing the carrier which preferably comprises coke particles with the tar sands, which mixture is then treated with an optimum amount of water and mixed so as to cause separation of oil-free sands and the enrichment of the remaining sands.

In various areas of the world, tar sands exist which contain various types of hydrocarbons as, for example, the heavy deposits of Athabaska tar sands existing in Canada. These sands contain tremendous reserves of hydrocarbon constituents. For example, the oil in the sands may vary from about to 21% by volume, generally in the range of about 12% by volume. The gravity of the oil ranges from about 6 to API, generally about 8 API. These sands may lie from about 200 to 300 it. below an overburden and the beds may range from about 100 to 400 ft. thick. A typical oil recovered from the sands has an initial boiling point of about 300 F. 1.0% distilled to 430 F., 20.0% distilled to 650 F. and 50.0% distilled to 980 F. However, the recovery of hydrocarbons in the past has not been effective to any great extent due to the deficiencies in operating techniques for the recovery of these hydrocarbons. For example, a relatively small amount of clay (from about 0% to 30%, usually about 5%) in the sand greatly retards recovery of the oil utilizing conventional Water techniques. Apparently the oil and the clay form skins which envelop small pockets of water often containing finely divided sand; then the enveloped pockets are distributed in water, thus forming a type of emulsion.

Numerous attempts have been made in the past to recover bitumen from the Athabaska tar sands in various manners. For example, it has been suggested that a solvent be added in order to reduce the viscosity of the bitumen, and in conjunction with water, to float the bitumen solvent mixture away from the sand. Although this technique achieves a good separation of clean sand, the addition of water results in problems with the formation of stable emulsions and sludges which have been very difficult to separate. Thus, extensive supplementary processing has been required in order to avoid large oil losses.

It has also been suggested in the past that tar sands as they are mined be handled by a thermal process in order to recover the bitumen therefrom. However, this process has been uneconomic-a1 due to the large amount of heat which is lost due to the fact that the heat is imparted to the sand and cannot be effectively and efiiciently recovered therefrom. It has been suggested for example that tar sands be handled in a direct fluid coking operation. However, as pointed out, this process is uneconomical for the reasons given above. Also, any process that will eiiectively handle tar sands must have the ability to handle a very wide range of tar sand and compositions which occur even in an immediate location. Some processes as, for example, direct fluid coking are able to handle these widely different compositions and, in accordance with the present process, employing a two-phase operation wherein in an initial phase a substantially richened tar sand is produced utilizing a granulated carrier as, for example, fiuid coke particles and wherein in the second phase the enriched sand is for example handled in a fluid coker, surprisingly effective results are secured.

The present invention may be readily understood by reference to the drawings illustrating the same. FIG- URE 1 illustrates the integrated process of the present invention wherein two phases are illustrated. In the first phase of the operation, enriched sands are produced and in the second phase of the operation, the enriched sands are handled in a manner to eiiicientiy recover the bitumen therefrom utilizing preferably a thermal operation. FIGURE 2 illustrates in some detail the criticality of utilizing the correct amount of water in the sand enrichment phase. This figure also illustrates the enhanced results secured by utilizing the granulated particles as for example fluid coke particles.

Referring specifically to FIGURE 1 illustrating an integrated process, tar sands as mined are introduced into a shearing-mixing stage or zone 3 of the sand separation phase by means of line 1. Water is introduced by means of line 2 and mixed with the sands. This water may be introduced directly into the shearing-mixing zone 3. It is also to be understood that while only one mixing zone is illustrated, a plurality of shearing-mixing zones may be used and a plurality of injection points also utilized. As a specific example, the composition of the sand introduced into zone 3 comprises about 6% by Weight connate water, 15% by weight of bitumen, about by weight of sand and about 5% clay. The clay content varies from about 0 to 30% in these sands but, in the specific example given, the clay comprises about 5% by weight of the total. In accordance with the present invention, the tar sandsas mined are mixed with granulated particles, preferably coke particles secured from a fluid coking operation, which are introduced by means of line 12. While it is preferred that these coke particles be mixed with the tar sands prior to the introduction of the water, it is within the concept of the present invention to add the granulated particles also by means of line 13 after the addition of the water. Under certain conditions, it may also be desirable to introduce the granulated particles directly into mixing zone 3 by means of line 14.

The mixing operation in zone 3 is carried out under conditions wherein a shearing thrust is imparted to the sands being mixed with the added water. Under these conditions, substantially oil-free sands separate and the entire mixture is passed into the second stage or zone of the sand separation phase which comprises a mechanical separation zone 5. The sands are introduced into zone 5 by means of line 4.

This mechanical separation zone may comprise any suitable mechanical means for separating the substantially oilfree sands from the bitumen-rich sands. For example, the mixture introduced by means of line 4 may be sieved in order to separate the oil-free sand which oil-free sand is removed by means of line 11. The bitumen enriched sands and granulated particles in a plastic physical state are removed by means of line 6 and passed into the second phase of the integrated process which preferably comprise a thermal operation, such as a fluid coking operation. This second phase, however, may comprise a solvent treating operation of the bitumen enriched sands. Stages 3 and 5 are preferably conducted at temperatures in the range from about 32 to 160 F., preferably at ten peratures in the range from 50 to 90 F.

As pointed out heretofore, it is preferred that zone '7 comprise a fluid coking operation such as described in US. Patent 2,881,130 issued April 7, 1959, entitled Fluid Coking of Heavy Hydrocarbons, inventor: Robert W. Pfeitfer et al. In essence, the fluid coking operation uses two vessels, a reactor and a burner, and solids are circulated between these to transfer heat to the reactor. The reactor will contain a fluid bed of the sticky enriched tar sands together with sticky coke particles. Reactor temperature averages from about 950 to 1100 F. and is controlled by the flow of hot coke from the burner. Pressure is about 0 to 50 pounds. Steam is introduced at the bottom of the reactor to fluidize the bed. The enriched sand feed may be introduced into the bed through a number of injection points. In the fluid coking operation, the mixing is good and the feed distributes uniformly over the surface of the particles. Here it cracks and vaporizes, leaving a sticky residue which slowly dries to form coke. The volume of vapors increases progressively up through the bed due to the formation of cracked products. Vapor products leave the bed and pass through cyclones which remove most of the entrained coke. The vapors then discharge into the bottom of the scrubber. Here the remaining coke thrust is scrubbed out and the products are cooled to condense out a heavy tar. The resulting slurry is recycled to the lower part of the coking reactor so that it is subjected to maximum cracking intensity. The upper part of the scrubber tower is a fractionation zone from which coker gas oil is withdrawn. Naphtha and gas oil are taken overhead to condensers.

In the reactor, the coke particles flow down through the vessel into a stripping zone at the bottom. Stripping steam displaces product vapors between the particles. The coke then flows down a standpipe, and through a slide valve which controls reactor bed level. A riser carries the coke up to the burner. Steam is added to the riser to reduce the solids loading and induce upward flow.

Average bed temperature in the burner is 1100-1150 F., air being added as needed to maintain the temperature by burning part of the product coke. If desired, extraneous oil fuel can be burned preferentially in order to increase coke production. Flue gases from the bed pass through two stages of cyclones, and discharge to the stack through a variable orifice which controls burner pressure. Hot coke from the burner bed is returned to the reactor through a standpipe, slide valve, and riser.

Since coke is one of the products of the process, it must be withdrawn from the system in order to keep the solids inventory from increasing. The coke product is removed from the burner bed through a quench-elutriator drum. Water is added to the latter to cool the coke, and make steam which entrains the fine particles and carries them back into the burner. Cooled coarse coke is withdrawn and sent to storage. In essence, the sand from the fluid coker will be removed with the coke and can be readily separated therefrom by mechanical separation or any other technique.

Typical operating conditions for fluid coking are as follows:

Reactor Burner 950 1, 10 11 1-3 2-8 Bed depth, ft 30-50 10-15 Reactor space velocity is expressed as w./w./hr., which means pounds of pitch fed per hour, per pound of coke holdup in the reactor. It is usually in the range of 0.5-1.0 w./w./hr. The slurry recycled to the reactor from the scrubber amounts to 20-40% on pitch feed. Coke circulation from the burner is about 5-40 pounds per pound of pitch feed. Thus, in FIGURE 1, hydrocarbon prod nets are diagrammatically shown as being withdrawn from the fluid coker by means of line 8, coke by means of line 9, and bitumen-free sand by means of line 10. In accordance with the preferred adaptation of the present inven tion, the coke particles moved by means of line 9 may be ground to the desired particle size and a portion of the same recycled to the mined tar sands by means of lines 12, 13, and 14 as hereinbefore described.

The effectiveness of the present technique for the sep aration of oil-free sand and the resulting production of bitumen enriched sand in the initial phase is illustrated in FIGURE 2. Referring specifically to FIGURE 2, the amount of water added is plotted along the abscissa and the amount of sand removed plotted along the ordinate. The connate water of the sand in FIGURE 2 is 7%. In all cases, the sand removed was substantially completely free from oil. It is apparent from FIGURE 2 that when less than about 40% of water is added, no oil-free sand separated whereas when the water added exceeded about 40% by weight, the amount of sand removed rose rapidly to apoint in excess of 65 to 75% bitumen-free sand. Thus, the remaining 35 to 40% of the sand contains the total amount of oil originally present on the total sand. As the water addition is increased, the amount of oilfree sand recovered decreases somewhat. Thus, it is preferred that the amount of water added in the present process be in the range from about 40 to 400% of water, preferably in the range from about 50 to 100% of water by weight based upon the tar sands being processed and that the preferred temperature be about 50 to 90 F.

It is also apparent from the present invention that, when utilizing approximately 25% of coke particles (8 to 14 mesh), increased quantities of oil-free sand were re moved.

The process of the present invention may be more fully understood by the following example illustrating the same. In operation A, the mined tar sands were mixed with water and handled in a manner as hereinbefore described. Operation B was similar to that with respect to operation A except that approximately 8 unit weights of coke particles were added per 25 unit weights of dry tar sands. The temperature at which the operation was carried out was in the range from 70 to 75 F. The results of these operations are as follows.

From the above it is apparent that the efiectiveness of operation B was 50% greater than operation A since Weight units of oil-free sand was removed as compared to 12.5 weight units in operation A.

If both the sand and the bitumen-carrier mixture are heavier than water, the separation can be performed under water by a mechanical operation such as by sieving. As pointed out heretofore, the bitumen is recovered from the enriched carrier and enriched sand by either coking the mixture and recycling the coke or separation of the carrier by subsequent commercial processing, such as water separation, Washing With solvent and centrifuging. Thus, the fluid coke added in the present invention, even though of the same particle size as the sand, completely takes up the bitumen in the agglomerate whereby sand is displaced. Furthermore, the coke added goes into the oil phase by virture of its hydrophobic character. The coke functions as a carrier for the oil thereby increasing the viscosity of the oil phase. The coke also functions as a scavenger for small oil particles, hence aiding agglomeration. By using hot fluid coke discharged from the coker a source of heat is provided and extremely eificient heat exchange with the sands is secured.

While the above integrated process has been described with respect to the preferred second phase utilizing a fluid type coking operation, it is to be understood that the enriched sands of the first phase may be treated by other techniques for the segregation of the concentrated bitumen from the sand. For example, the second phase of the integrated process may comprise a solvent treating technique utilizing various hydrocarbon solvents such as gas oils, naphtha, and the like. It is also within the scope of the present invention to utilize, in the second phase, a delayed coking technique. In this delayed cok ing technique, the enriched sands are heated and introduced into a soaking drum which provides the long residence time needed for cracking. The cracked products leave at the top and the co \e-sand deposit remain in the bottom of the drum. In order to provide semi-continuous operation, a plurality of drums may be utilized. The amount of agglomerate added as compared to the dry sands may vary appreciably as in the range from about Wt. percent to 16 wt. percent. However, when utilizing coke particles as, for example, fluid coke particles, it is preferred that the amount of coke particles added based upon dry sands is in the range from about 10 wt. percent to 35 Wt. percent, preferably about 25 wt. percent. It is also preferred that the size of these coke particles approxmiate that of the size of the sand particles and have a particle size in the range from about 6 to 20 mesh, preferably about 8 to 14 mesh.

What is claimed is:

1. Improved process for producing enriched bitumen tar sands from natural tar sands which comprises adding a granulated carrier consisting essentially of coke particles to said natural tar sands, thereafter adding from about 40% to 400% by weight of a fiuid consisting essentially of Water to the sands and subjecting the mixture to a mixing-shearing action at a temperature in the range from about 32 to 160 F., thereafter subjecting the mixture to a mechanical separation operation wherein substantially bitumen-free sands separate from enriched bitumen sands.

2. Process as defined by claim 1 wherein said coke particles are coke particles secured from a fluid coking 6 operation and wherein the same are present in a concentration of about 10 to wt. percent based upon dry sands.

3. Process as defined by claim 1 wherein the amount of Water added is in the range from about to about 100% and wherein the temperature is in the range from about F. to about 98 F.

4. Improved integrated process for the recovery of oil from natural tar sands which comprises adding from about 10% to 35% by weight of a granulated carrier consists essentially of coke particles to said natural tar sands and in a first phase adding from about 40% to 400% by weight of a fluid consisting essentially of water to said tar sands and subjecting the mixture to a mixingshearing action at a temperature in the range from about 32 F. to about 160 F., thereafter subjecting said mixture in said first phase to a mechanical separation process whereby from about -75% of substantially oil-free sands separate from an enriched oil tar sands, thereafter in a second phase subjecting said enriched tar sands to a thermal recovery process and separating oil and coke from said enriched sands.

5. Process as defined by claim 4 wherein the temperature in said first phase is in the range from about 32 to F. and wherein the temperature in said second phase is in the range from about 800 to 1400 F.

6. Process as defined by claim 5 wherein said thermal process comprises a coking process.

7. Process as defined by claim 6 wherein said coking process comprises a fluid coking process.

8. Improved process for producing bitumen-enriched tar sands from natural tar sands which comprises adding from about 10% to 35% by weight of a granulated carrier consisting essentially of coke particles to said natural tar sands, thereafter adding from about 40% to 400% by Weight of Water to the tar sands, thereafter subjecting the mixture in an initial stage to a mixingshearing action at a temperature in the range from about 32 to F., thereafter in a secondary stage subjecting the mixture to a mechanical separation operation wherein substantially from about 6575% oil-free sands separate from bitumen-enriched tar sands.

9. Process as defined by claim 8 wherein the temperature in both stages is in the range from about 32 to about References Cited in the file of this patent UNITED STATES PATENTS 5 1,420,165 Trent June 20, 1922 2,609,331 Cheney Sept. 2, 1952 2,881,130 Pfeiffer Apr. 9, 1959 2,886,514 Grifiin et a1 May 12, 1959 55 FOREIGN PATENTS 523,067 Canada Mar. 20, 1956 586,229 Canada Nov. 3, 1959 609,876 Canada Dec. 6, 1960 OTHER REFERENCES 

1. IMPROVED PROCESS FOR PRODUCIONG ENRICHED BITUMEN TAR SANDS FROM NATURAL TAR SANDS WHICH COMPRISES ADDING A GRANULATED CARRIER CONSISTING ESSENTIALLY OF COKE PARTICLES TO SAID NATURAL TAR SANDS, THEREAFTER ADDING FROM ABOUT 40% TO 400% BY WEIGHT OF A FLUID CONSISTING ESSENTIALLY OF WATER TO THE SANDS AND SUBJECTING THE MIXTURE TO A MIXING-SHEARING ACTION AT A TEMPERATURE IN THE RANGE FROM ABOUT 32* TO 160*F., THERAFTER SUBJECTING THE MIXTURE TO A MECHANICAL SEPARATION OPERATION WHEREIN SUBSTANTIALLY BITUMEN-FREE SANDS SEPARATE FROM ENRICHED BITUMEN SANDS. 